The present invention is directed to toner compositions, and developer materials containing such compositions. More specifically, the present invention is directed to red toner compositions containing as a pigment, certain alkaline earth salts of sulfonic acids as described hereinafter. These salts when incorporated into the toner resin, either alone, or in combination with other pigments result in color developer compositions useful in a number of imaging systems, including electrostatographic imaging systems. Additionally, the toner and developer compositions of the present invention may contain additives such as charge enhancing additives, and such compositions can be utilized to develop negative electrostatic latent images, or positive electrostatic latent images.
Colored developing compositions comprised of resin particles, carrier particles, and pigments consisting of magenta, cyan and/or yellow materials are well known, for example, reference U.S. Pat. No. 4,066,563. There is disclosed in this patent color developing compositions containing certain specific cyan, magenta and yellow pigments, which developer compositions when employed together with specific carrier materials were found to be highly useful in developing color images. The intensity of the color desired is dependent not only on the concentrations of the pigments employed, but on other factors including the carrier material utilized, and the specific composition of the pigment added to the toner resin. Thus, for example, certain types of yellow pigments when used with magenta and cyan pigment result in the production of colored images containing a certain yellow intensity, for example, the yellow might be classified as a light yellow as compared to a bright yellow. Similarly, when certain red pigments are employed in electrostatic imaging systems there can result images of a low or high red intensity, that is the red color can range from the light red or pink to a deep red in some instances.
Commercial acceptance of color is dependent on a number of considerations including the pleasing nature of the color to the final user. The hue and/or chroma of the final color may be satisfactory to one individual, and not satisfactory to another. In some instances, the hue or chroma of the color is not satisfactory to a substantial number of individuals resulting in rejection of the final developed copies and failure from a commercial standpoint of the imaging device utilizing such developer compositions. Accordingly, there continues to be a need for the development of improved pigments, and color developing compositions containing same.
Additionally, some of the prior art pigments are not compatible with the toner resins and/or carrier particles utilized, and in some instances the pigments are incompatible with other pigments employed in the developing composition. Furthermore, several prior art developer compositions containing cyan, magenta and yellow pigments possess unsatisfactory hue and chroma, are sensitive to relative humidity, have slow admix charging, and unsatisfactory triboelectric charge in some instances.